Process for treating red meat to control bacterial contamination and/or growth

ABSTRACT

The surface of red meat is treated with an trialkali metal orthophosphate to reduce, remove, retard or control salmonella, campylobacter, E. coli, and spoilage bacteria without causing organoleptic depreciation of the meat, including color change.

This is a continuation-in-part application of U.S. application Ser. No. 931,138, filed Aug. 17, 1992, now U.S. Pat. No. 5,268,185 which is a continuation of U.S. application Ser. No. 712,245, filed, Jun. 7, 1991, now U.S. Pat. No. 5,192,570.

The present invention relates to an improved process for reducing the level of and retarding the growth of bacteria, on newly slaughtered raw red meat carcasses without causing organoleptic depreciation thereof.

BACKGROUND OF THE INVENTION

The invention relates to a treatment step made during slaughter of fresh meat and more particularly to treating pork, beef, veal, mutton, lamb and goat carcasses with a solution of alkali metal orthophosphate to remove, retard or reduce bacterial contamination and/or growth without causing substantial organoleptic depreciation of the meat.

Red meat, during and after slaughter, may contain or become contaminated with certain undesirable bacteria such as salmonella, campylobacter, listeria, E. coli, spoilage bacteria, and the like. The red meat is processed by removing the hide, eviscerating, cooling and cutting into larger cuts for fresh, cured meat or boxed meat. The fresh red meat obtained after evisceration is chilled by hanging the sides of red meat at a temperature usually below 10° C. Beef is hung for a considerable period to allow natural enzymes to tenderize the beef. Pork is simply cooled. For certain primal cuts, such as ham, bacon, corned beef and pastrami the cuts are cured by chilling below 10° C. followed by injection of a solution containing salt, nitrite and/or nitrate, sweetener, cure accelerator, one or more polyphosphates, spices and flavorings. The meat is prepared to 105% to 130% of its weight with curing solution. Boxed meat is cut into primal cuts after chilling, vacuum packaged and boxed.

As disclosed in Zyss U.S. Pat. No. 3,782,975, primal cuts of red meat are maintained between 32°-42° F. (for about 3 to 5 days). During that period, the sodium nitrite reacts with the myoglobin of the meat to form nitrosomyoglobin which insures good color to the meat. The addition of the curing solution to the primal cuts imparts improved texture, tenderness, flavor and color that would be lacking if the curing brine was not added to the meat. Zyss teaches that for people with a sodium problem, a pumping solution of potassium salts including potassium orthophosphates could be employed.

A second patent to Zyss, U.S. Pat. No. 3,775,543, suggests the addition of phosphate compositions including potassium orthophosphates to processed meats as a binding agent in from 0.2 to 2.0% by weight of the mix. Zyss clearly avoids alkaline pH since he indicated that alkaline pH decreases the meat's shelf life. Zyss neutralizes with acid to pH 6.4 to 6.8. In example II, Zyss prepares a bologna product using about 1% tripotassium orthophosphate. Surprisingly, we have found that surface orthophosphate treatment increased shelf life.

Ueno, et al. U.S. Pat. No. 4,592,892, uses ethanol to sterilize certain food and processing machinery and may employ a carbonate and/or trialkali orthophosphate combined with the ethanol to enhance the ethanol's effectiveness.

Several patents to Swartz, U.S. Pat. No. 3,493,392, U.S. Pat. No. 3,620,767, and Canadian Patent No. 847,280, use phosphates including sodium orthophosphate as a processing aid for fish.

Bynagte, U.S. Pat. No. 3,705,040, uses phosphates to help remove shrimp from their shells. Sodium orthophosphate at 2-15% with other ingredients can be employed.

Cheng, U.S. Pat. No. 4,683,139, teaches a process for obtaining prepackaged fresh meat at retail wherein the shelf life of the meat is increased by treatment with an aqueous solution of an alkali metal salt of certain phosphate compounds, a reducing compound such as ascorbic acid and a sequestering or chelating agent such as citric acid. The phosphate can be an orthophosphate, pyrophosphate, tripolyphosphate or hexametaphosphate. Meat pH is below neutral.

Szczesniak et al., U.S. Pat. No. 4,075,357, teaches salt combined with a secondary salt selected from alkali metal salts of organic acids and trisodium orthophosphate, polyphosphate, metaphosphate and ultraphosphate. Citrates are preferably combined with sodium chloride. These mixtures are used to control water activity in intermediate moisture cooked food.

Kohl, et al., U.S. Pat. No. 3,681,091, teaches treating foods including fish fillet with 10% solutions of medium chain length polyphosphates.

Freund, et al., U.S. Pat. No. 2,957,770, teaches improving the properties of meat with a casein composition which can include inorganic orthophosphates such as disodium hydrogen orthophosphate.

Many treatment systems for poultry have been suggested. It has been reported that the thermal death rate of salmonellae can be increased during scalding by elevating the pH of the scald water to pH 9.0+0.2. Agents such as sodium hydroxide, potassium hydroxide, sodium carbonate, and trisodium phosphate have been reported as effective pH adjusting agents for use in increasing the thermal death rate of the bacteria. Trisodium phosphate was reported as least effective in increasing the death rate. See "The Effect on pH Adjustment on the Microbiology of Chicken Scald-tank Water With Particular Reference to the Death Rate of Salmonellae", T. J. Humphrey, et al., Journal of Applied Bacteriology 1981, 51 pp. T. J. Humphrey, et al. have also reviewed the pH effect of scald water on Salmonella on chicken skin. See "The Influence of Scald Water pH on the Death Rates of Salmonella typhimurium and Other Bacteria Attached to Chicken Skin", Journal of Applied Bacteriology 1984, 57 (2), pp. 355-359. Scald water adjusted to pH 9±0.2 as in the 1981 paper can help to reduce external and internal cross-contamination of carcasses by salmonellas.

"Phosphate and Heat Treatments to Control Salmonella and Reduce Spoilage and Rancidity on Broiler Carcasses", J. E. Thompson, et al., Poultry Science, 1979, 58, 139-143 teach kenaphosphate, a blend of 90% sodium tripolyphosphate and 10% sodium hexametaphosphate did not consistently or effectively effect either salmonella survival or total bacterial count.

Attempts have been made to pasteurize poultry meat by treating the meat with a solution containing agents such as lactic acid, acetic acid, sodium carbonate, sodium borate, sodium chloride, potassium hydroxide, chlorine and EDTA. All treatments, except sodium borate, sodium chloride, and sodium carbonate reduced the visual acceptability of the meat. Chlorine failed to destroy bacteria on the surface of the poultry but would be expected to control salmonellae in water. See Chemical Pasteurization of Poultry Meat, J. S. Teotia, Disseration Abstracts Int'l. B., 1974, 34(a), 4142. It is known that the shelf life of chicken carcasses can be increased 1 to 2 days by chilling the poultry in a solution of 6% sodium tripolyphosphate/0.7% tetrasodium pyrophosphate (Kena-available from Rhone-Poulenc, Inc., Food Ingredients Division). See The Antimicrobial Effect of Phosphate With Particular Reference To Food Products, L. L. Hargreaves, et al., The British Food Manufacturing Industries Research Association, Scientific and Technical Surveys, No. 76, April 1972, Pages 1-20 at Page 12. Many patents and articles suggest the use of polyphosphates in preserving meat and fish products.

In addition, it is also stated in the Hargreaves reference at page 7 that G. Pacheco and V. M. Dias in an article entitled Bacteriolytic Action of Phosphates, Mems Institute Oswaldo Cruz, 52 (2) ppg. 405-414, reported on the bacteriolytic action of solutions of monosodium, disodium, trisodium and dipotassium orthophosphates on dead and living cells of Salmonella typhosa, Escherichia coli and Staphylococcus aureus. Trisodium phosphate dodecahydrate is stated to have the greatest lytic action. The reference does not relate to treating meat or fish.

British patent 935,413 teaches treating raw poultry in the chill tank with a non-cyclic polyphosphate. It is taught that this method provides increased preservation of the poultry flesh by decreasing exudate and thereby decreasing spread of bacteria.

Trisodium phosphate has also been found to be effective in inhibiting the growth of blue mold in cuts and bruises in fruit by treating the broken surface with the solution of trisodium phosphate (U.S. Pat. No. 1,774,310 ).

Trisodium orthophosphate is also a known and widely used anticaking agent (see U.S. Pat. No. 2,770,548).

SUMMARY OF THE PRESENT INVENTION

In accordance with the present invention, there is provided a process for treating red meat carcasses and organs to remove, reduce or retard bacterial growth, such as salmonella, campylobacter, E. coli, and spoilage bacteria, without affecting the organoleptic properties of the meat. The process comprises surface treating the red meat carcasses or organs, preferably prior to rigor, by contacting the surfaces with a solution of trialkali orthophosphate above pH 11.5 without appreciably changing the color of the meat by causing a darkening of the muscle tissue resulting from high pH. By contacting the red meat prior to rigor, however, lactic acid produced during rigor partially or totally neutralizes the trisodium orthophosphate and further reduces any adverse pH effect on color. Alternatively, a water and/or acid wash may be employed to neutralize any orthophosphate remaining on the surface after treatment.

The treatment is preferably conducted during slaughter either prior to or after chilling by dipping or preferably spraying the orthophosphate solution onto all surfaces of the carcass or organs for several minutes. Preferable treatment is done before rigor on set.

Specifically, it has been discovered that pork, beef, veal, mutton, and goat carcasses and organs can be treated with from about 4% to saturation of a solution of trisodium or tripotassium orthophosphate dodecahydrate or an equivalent amount of the anhydrous compound.

By use of this process the carcass and organs can be treated economically and simply with a food grade product to achieve salmonella and other bacteria control without organoleptic depreciation of the carcass and organs. Other benefits are evident from the description that follows.

DETAILED DESCRIPTION OF THE INVENTION

Trialkali metal phosphate is an orthophosphate salt of the formula R₃ PO₄ with a formula for the sodium salt being Na₃ PO₄ and an equivalent formula for the tripotassium compounds. R is an alkali metal of sodium or potassium. Trisodium phosphate has a minimum of 41.5% P₂ O₅ and a typical pH in a 1% solution of about 11.8.

Trisodium phosphate is available as the dodecahydrate and in commerce the dodecahydrate is available in technical or food grade. Preferably the dodecahydrate (ether form) is used. As used herein trisodium phosphate is intended to include tripotassium phosphate as well as all forms of those compounds.

The invention is applicable to any red meat including pork, beef, veal, mutton, lamb and goat either whole carcass or fresh parts, including internal organs such as hearts, kidneys and livers, preferably before rigor.

After the animal is killed, bled, skinned and eviscerated, the carcass is normally chilled. The carcass surface and/or organs is then treated with a trialkali metal orthophosphate either before, during or after chilling. The carcass is treated with a treatment solution containing from about 4% to saturation, preferably from about 6% and more preferably from about 8% to saturation of trialkali metal orthophosphate by weight of solution. From about 4% to 20%, preferably 6-15%, and most preferably from about 8% to 12% orthophosphate have been effective, particularly at chilled temperatures.

The carcass can be dipped in the treatment solution preferably with solution agitation to increase contact of the treatment solution with all surfaces and crevices of the carcass, including the internal organs. The treatment solution is preferably applied by mechanical sprayers, usually under high pressure to insure good contact of the treatment solution with the meat surface. The treatment solution preferably contains only trialkali metal orthophosphate as the means to control, reduce, retard or remove bacteria. No alcohol, nitrate or nitrite, or ascorbic acid is employed in the treatment solution for purposes of enhancing the effect of the orthophosphate. The treatment solution may contain other ingredients for water binding, cleaning, flavoring, coloring and the like. Salts may be used, including chlorides and the like. Normally, except in pumping solutions, other phosphates are not combined with the orthophosphate.

The treatment solution preferably comprised of trialkali metal orthophosphate in an amount sufficient to provide a pH above about 11.5 and preferably within a range from 11.6 to 13.5 and most preferably from about pH 12 to pH 13.5.

The treatment solution is employed before, during or after evisceration and preferably before rigor. While any temperature application is possible, it is preferred to treat the carcass at a temperature which does not cause flavor, color or appearance change usually at about the carcass temperature. In many cases the treatment solution temperature is below 40° C., preferably equal to or below about 27° C. When treating chilled meat, this temperature could be below 10° C. However, temperatures of up to 60° C. may be used to yield efficacious results. Preferably the red meat is treated either before or directly after skinning and usually prior to chilling with a solution consisting essentially of trialkali orthophosphate at from 4% to saturation.

The carcass surface is contacted with the treatment solution for a period of time sufficient to remove, retard or reduce bacterial contamination and/or growth over and above that obtainable if pure water were used. Treatment dwell time is sufficient, under conditions of treatment, to contact all contactable exposed surface of the carcass, effecting a washing of the surfaces. If desired, a layer of orthophosphate may be left on the carcass to prevent or retard further bacterial growth so long as significant discoloration of the carcass or resulting cut meat products is avoided.

At atmospheric pressure, in a dip tank, dwell times from 5 seconds to about 30 minutes are effective, while dwell times using a spray range from several seconds to several minutes or 2 seconds to 15 minutes with spray times of less than 30 seconds preferred.

The high pH of over 11.5 preferably about pH 12 or above is critical to remove, reduce or retard bacterial contamination or growth. The mechanism is not entirely understood, but the orthophosphate appears to improve bacterial removal as well as retarding growth of any residual bacteria.

In a preferred embodiment of this invention, red meat is treated with trialkali metal orthophosphate prior to pumping cuts of meat with salts, nitrate and the like. The trialkali metal phosphate treatment prevents bacteria from being driven into the meat during pumping which could result in later spoilage. By treating the surface first with orthophosphate any bacteria are removed or controlled prior to the pumping operation.

If treated before rigor, the lactic acid generated from rigor assists in controlling any browning of muscle meat.

We have found the trialkali metal orthophosphate is effective against salmonella, campylobactar, E. coli, spoilage bacteria and the like.

EXAMPLE 1 Carcass Preparation

A barrow was slaughtered and split in half. The right side was used as Control and the left side was treated with trisodium orthophosphate (TSP). One hour and fifteen minutes post-slaughter (pre-rigor), the left side was totally submerged in a solution (pH 13.14) containing 10% TSP for 2 minutes, then subsequently placed in a 38° F. cooler with the control for 48 hours.

Microbiological Procedures

Fifteen minutes following treatment, both Control and orthophosphate carcasses were surface swabbed at two locations at a portion of the belly parallel to the 10th rib and an area on the carcass exterior (skin) directly opposite the 10th rib sampling location.

The areas were swabbed (18 strokes) with a sterile bent glass rod. The rod was then placed in 50 ml of a phosphate buffer (pH 6.0). One milliliter of the 50 ml solution was then diluted in a 9 ml phosphate buffer (pH 6.0). A total of 6 dilutions were performed. After dilution, 1/10 ml was placed in a petri dish containing a pre-poured agar with 10% sheep's blood. The dishes were incubated for 48 hours at 34° F. Total plate counts were then conducted.

A 48 hour swabbing was also conducted in the same manner as previously mentioned but at 5 different locations. These locations were as follows:

1. Parallel the anterior end of the aitch bone.

2. Diaphragm muscle located ventral to the 10th rib.

3. Jowl region.

4. Skin of the ham opposite the aitch bone.

5. Skin of the shoulder opposite the 2nd rib.

Meat pH

A meat sample was obtained from the anterior end of the aitch bone (location 1) and the belly located ventral to the 10th rib (location 2). A surface pH was taken on each sample. The meat sample was then ground and a composite pH was taken.

                  TABLE 1                                                          ______________________________________                                         pH of Hog Carcasses                                                                        pH                                                                 Sample Location                                                                              Sample Surface                                                                             Ground Sample                                        ______________________________________                                         Control:                                                                       Ham - Anterior to                                                                            6.77        5.96                                                 the aitch bone                                                                 Belly - Ventral                                                                              6.58        5.72                                                 the 10th rib                                                                   TSP Treated                                                                    Ham - Anterior to                                                                            6.84        5.99                                                 the aitch bone                                                                 Belly - Ventral                                                                              6.90        5.89                                                 the 10th rib                                                                   ______________________________________                                    

Table 1 shows that the surface pH was greater than the ground sample pH but this difference was not greater than 1.0 pH point at any given location. The TSP treated sample pH was greater than the control for both surface and ground sample pH readings. However, the greatest pH difference was 0.32 between the surface pH of the control belly and TSP belly. These findings suggest that the little difference between the control and TSP would have no effect on processing or consumer preference.

1.5 Hours Post-Slaughter

There was no distinct visual differences between the control and the TSP treated carcass. The TSP treated carcass did have a slightly darker pigment color but was not that easily recognizable. The total plate count conducted was inconclusive for both the control and TSP.

48 Hours Post-Slaughter

Visual appearance at this time period was very similar to the 1.5 hour post-slaughter, showing little difference in muscle pigment color between the control and TSP.

                  TABLE 2                                                          ______________________________________                                         Total Plate Count 48 Hours Post-Slaughter                                      Location       0 Dilution                                                      ______________________________________                                         Control:                                                                       1              18                                                              2              15                                                              3              12                                                              4              1                                                               5              5                                                               TSP Treated                                                                    1              0                                                               2              0                                                               3              0                                                               4              0                                                               5              0                                                               ______________________________________                                    

The Total Plate Count (Table 2) showed bacterial growth in the nondiluted control sample but not the TSP treated sample. The greatest growth was found at the aitch bone followed by the belly, jowl, shoulder (skin) and ham (skin). There was no growth recorded in the dilutions for either the control or TSP treatment.

This Example shows a surprising lack of discoloration of a paired split hog carcass treated pre-rigor with trisodium orthophosphate.

This Example clearly shows the ability of trisodium phosphate to control bacterial growth on a hog carcass without affecting the visual appearance of the lean muscle. A 10% trisodium orthophosphate solution was used to submerge the hog carcass for a two minute time treatment and gave a complete reduction of total plate count based on 48 hour swabbing done at various locations on the carcass.

EXAMPLE 2

Pieces of beef flank and loin are dipped in 130° F. (54° C.) water and several different (130° F.) trisodium orthophospate (TSP) solutions (1%, 4%, 10%, 20%) for 3 and 15 seconds. The samples are stored in a 34° F. (1° C.) cooler for 18 hours.

Initially and after the 18 hour storage, there are no visual differences between the water and TSP treated samples. These observations are made on the outer muscle membrane/lean and fat as well as the cross section of each sample. While not microbiologically evaluated, it is hypothesized that the TSP treatment solutions having a concentration of greater than 4% would effectively reduce or retard the growth of pathogenic microorganisms on the beef carcass.

The results demstrate that there should not be any adverse effects on the color of a beef carcass sprayed with a 130° F. TSP solution.

EXAMPLE 3

A study is conducted to visually determine if a trisodium orthophosphate (TSP) solution would affect the color of organ meats. The organ meats studied are beef heart, liver and kidney and pork heart and kidney.

Four of each organ meat are sliced in half, so the control dip (130° F.) could be compared to the TSP dip from the same organ meat, and assigned to one of the following solutions:

1. Control--tap water at 130° F. (54° C.).

2. 10% TSP solution at 70° F. (room temperature) (21° C.).

3. 10% TSP solution at 130° F. (54° C.).

4. 20% TSP solution at 130° F. (54° C.).

The Control and TSP treatments for the same organ meat are dipped simultaneously for 15 seconds. The organ meats are set on trays and visually analyzed 15 minutes post-treatment. The samples are stored in a 34° F. cooler for another visual analysis after 18 hours.

The results of the visual analysis are extremely positive. The only detectable difference is a slightly redder color of the TSP treated beef and pork hearts but this is favorable rather than unappealing.

While not microbiologically evaluated, it is hypothesized that the TSP treatment solutions having a concentration of greater than 4% would effectively reduce or retard the growth of pathogenic microorganisms on the beef carcass.

EXAMPLE 4

Determination of the Effects of TSP on Escherichia coli 0157:H7 and Salmonella typhimurium Attached to Beef Lean and Fatty Tissues

METHODOLOGY

1. Escherichia coli 0157:H7 (USDA/FSIS 45956; meat isolate) a bacteria which can cause serious illness, including death, in man if ingested, and Salmonella typhimurium stock cultures were activated by growing each culture individually in Tryptic Soy Broth (TSB) at 37° C. for 18 h. These activated cultures were transferred to individual flasks containing 250 ml of TSB and incubated again for 18 h at 37° C. Contents of the two flasks were centrifuged at 5000 X g for 10 min at 4° C. The cell pellet of each culture was resuspended in 5 mL of 0.1% peptone water buffer and 2 mL from each suspension transferred and mixed in a sterile tube (providing a cell concentration of approximately 10¹⁰ CFU/mL for each pathogen. The mixed inoculum was further diluted to 10⁹ CFU/mL and 1 mL of this inoculum transferred to 250 mL of peptone water as the final inoculum (ca. 10⁷ CFU/mL) for dipping of samples. This inoculum was plated onto Bismuth Sulfite Agar (BSA) and MacConkey Sorbitol Agar (MSA) to determine actual inoculum numbers for S. typhimurium and E.coli 0157:H7, respectively.

2. This mixed inoculum was divided into two 125 mL portions.

3. Lean and fatty portions of beef are cubed (as aseptically as possible) into 2 cm³ portions and placed into individual sterile sample jars which are refrigerated (2° C.) until needed the following day.

4. Each group (lean or fat) of four cubes are dipped into a separate beaker of inoculum for 5 min, removed from the solution and placed on sterile absorbant filter paper for 5 min to absorb excess inoculum.

5. Each group of four cubes are then placed into a stomacher bag to which 250 mL of diluent is added. The bag is inverted 25 times in a gentle manner to remove bacterial cells that are unattached to the meat or fat surfaces.

6. Each cube is transferred individually to a sterile container for trisodium orthophosphate (TSP) treatment.

7. Individual beakers containing 100 mL of the specified percent solution of TSP (0, 1, 4 or 10%; W/V basis) are prepared for each cube. The meat or fat cube is completely submerged in the specified TSP solution at room temperature for 5 sec.

8. After the 5 sec immersion period, each cube is placed into an individual stomacher bag in 30 mL of diluent and mixed for 2 min. These samples are assayed for Salmonella and E. coli 0157:H7 using BSA and MSA, respectively, by spiral plating techniques (all samples are plated in duplicate. Typical colonies are confirmed by serological techniques; polyvalent 0 antisera and latex agglutination (Oxoid) for Salmonella and E. coli 0157:H7, respectively) .

9. Surviving pathogen numbers are reported as log₁₀ CFU/cm² of sample using the average counts of duplicate plates.

All experiments are replicated; yielding "REP 1" and "REP 2" samples.

                  TABLE 3                                                          ______________________________________                                         RESULTS OF EXPERIMENTS                                                                      LOG CFU/CM.sup.2                                                  Sample                                                                               REP      % TSP   S. typhimurium                                                                             E. coli 0157:H7                             ______________________________________                                         lean  1        0       5.02        4.90                                        beef           1       4.84        4.88                                                       4       4.85        *                                                          10      4.61        4.48                                        fat            0       5.14        5.84                                        beef           1       5.23        5.28                                                       4       4.02        4.18                                                       10      3.63        3.63                                        lean  2        0       4.23        4.15                                        beef           1       4.00        4.40                                                       4       3.92        4.20                                                       10      3.96        4.05                                        fat            0       4.81        5.01                                        beef           1       4.30        4.97                                                       4       3.38        4.20                                                       10      2.17        2.85                                        ______________________________________                                          *erroneous data point                                                    

The above data demonstrates that treatment of both lean and fatty issue of beef with 4% TSP, and particularly 10% TSP solutions is effective against both Salmonella and E. coli 0157:H7. Efficacy is particularly pronounced in treating fatty beef tissue. For example, treatment of fatty beef tissue with a 10% TSP solution shows about at least a 2 log reduction in both Salmonella and E. coli.

EXAMPLE 5

Fresh beef round chunks are purchased from a local market. Chunks weighing between 2 and 4 lbs are inoculated with E. coli 157:H7. Ten L volumes of E. coli 0157:H7 inoculum Butterfield's Phosphate Buffer (BPB) suspension are used to inoculate 12 meat chunk samples at a time. Meat chunks are immersed in the inoculating medium for 1 min. and then removed and allowed to drain for 1 min. on paper towels in another container. Six of these meat chunks are rinsed with 10% TSP at 70° F. for 15 sec., 6 are rinsed with water at 70° F. for 15 sec. Another batch of inoculated 12 meat chunk samples are rinsed with 15% TSP at 120° F. for 15 sec., and 6 are rinsed with water at 120° F. for 15 sec.

One chunk from each set of six chunks is used per sampling interval and discarded afterwards. Samples are excised aseptically at sites of the meat chunk that have natural meat membranes or are covered with a fat layer. Samples have approximate dimensions of 8×8 cm with a thickness of 0.5 cm (3×3×0.25 in), such that 25 g of meat are cut and tested for E. coli 0157:H7.

Table 4 shows results of triplicate experiments evaluating the effect of 10% TSP (15 sec. at 70° F.) against E. colt 0157:H7 in inoculated beef after various post-rinsing time intervals. Water-rinsed control beef (15 sec. at 70° F.) that are sampled at similar intervals are also shown in Table 4. At time 0, trials 1, 2, and 3 shows an instant reduction of 1.0, 1.34, and 2.1 log cycles in E. coli 0157:H7 numbers, respectively, after rinsing of beef with 10% TSP than after rinsing with water, under the same conditions. Sampling after various post-rinsing intervals does not show any consistent trend in the reduction of E. coli 0157:H7 numbers. However, looking at Table 6, which summarizes the 3 trials, (mean values), E. coli 0157:H7 numbers recovered are always lower (0.28-1.85 logs) in meat samples that are rinsed with 10% TSP.

Results of the triplicate experiments evaluating the effect of 15% TSP (15 sec. at 120° F.) against E. coli 0157:H7 in inoculated beef after various post-rinsing time intervals are shown in Table 5. Water-rinsed control beef (15 sec. at 120° F.) that are sampled at similar intervals are shown in Table 5. At time 0, trials 1, 2, and 3 show an instant reduction of 1.0, 0.79, and 1.65 log cycles in E. coli 0157:H7 numbers, respectively, after rinsing of beef with 15% TSP than after rinsing with water, under the same conditions.

Sampling after various post-rinsing intervals does not show any consistent trend in the reduction of E. coli 0157:H7 numbers. However, looking at Table 6, which summarizes the 3 trials (mean values), E. coli 0157:H7 numbers recovered are always lower (0.12-1.78 logs) in meat samples that have been rinsed with 15% TSP at 120° F., than in water.

In summary, the results of experiments demonstrate that 10 and 15% TSP solutions, at 70° and 120° F., respectively, can be effective in reducing the viable E. coli 0157:H7 population in laboratory model inoculated beef. Exposure to residual 15% TSP shows a further 1/2 log reduction in E. coli 0157:H7 numbers after 24 h.

                                      TABLE 4                                      __________________________________________________________________________             Trial 1   Trial 2   Trial 3                                            Sampling Time                                                                          H.sub.2 O                                                                           10% TSP                                                                             H.sub.2 O                                                                           10% TSP                                                                             H.sub.2 O                                                                           10% TSP                                       __________________________________________________________________________     0       2.3 × 10.sup.4                                                                2.3 × 10.sup.3                                                                4.6 × 10.sup.5                                                                2.1 × 10.sup.4                                                                2.9 × 10.sup.4                                                                2.3 × 10.sup.2                          15 s    1.5 × 10.sup.3                                                                2.1 × 10.sup.3                                                                9.3 × 10.sup.4                                                                1.5 × 10.sup.4                                                                4.3 × 10.sup.4                                                                1.5 × 10.sup.4                          5  min  9.3 × 10.sup.4                                                                4.3 × 10.sup.4                                                                4.3 × 10.sup.4                                                                4.3 × 10.sup.4                                                                2.1 × 10.sup.5                                                                4.3 × 10.sup.3                          1  h    1.5 × 10.sup.5                                                                2.3 × 10.sup.4                                                                1.6 × 10.sup.4                                                                4.3 × 10.sup.3                                                                2.3 × 10.sup.4                                                                9.3 × 10.sup.2                          6  h    2.4 × 10.sup.5                                                                2.3 × 10.sup.4                                                                1.5 × 10.sup.5                                                                9.3 × 10.sup.4                                                                4.3 ×  10.sup.3                                                               7.5 × 10.sup.2                          24 h    4.6 × 10.sup.5                                                                2.4 × 10.sup.5                                                                9.3 × 10.sup.2                                                                4.3 × 10.sup.2                                                                3.6 × 10.sup.3                                                                4.3 × 10.sup.2                          __________________________________________________________________________      Data represent most probable number MPN/g beef.                          

                                      TABLE 5                                      __________________________________________________________________________             Trial 1   Trial 2   Trial 3                                            Sampling Time                                                                          H.sub.2 O                                                                           15% TSP                                                                             H.sub.2 O                                                                           15% TSP                                                                             H.sub.2 O                                                                           15% TSP                                       __________________________________________________________________________     0       9.3 × 10.sup.4                                                                9.3 × 10.sup.3                                                                9.3 × 10.sup.3                                                                1.5 × 10.sup.3                                                                9.3 × 10.sup.4                                                                2.1 × 10.sup.3                          15 s    9.3 × 10.sup.4                                                                9.3 × 10.sup.3                                                                7.5 × 10.sup.4                                                                1.5 × 10.sup.3                                                                2.1 × 10.sup.3                                                                2.8 × 10.sup.2                          5  min  2.0 × 10.sup.3                                                                1.5 × 10.sup.3                                                                2.3 × 10.sup.4                                                                2.3 × 10.sup.4                                                                7.5 × 10.sup.3                                                                4.3 × 10.sup.2                          1  h    4.6 × 10.sup.4                                                                9.3 × 10.sup.3                                                                9.3 × 10.sup.3                                                                1.5 × 10.sup.4                                                                1.2 × 10.sup.4                                                                7.5 × 10.sup.2                          6  h    1.5 × 10.sup.4                                                                2.1 × 10.sup.2                                                                1.2 × 10.sup.5                                                                2.3 × 10.sup.3                                                                7.5 ×  10.sup.3                                                               2.8 × 10.sup.1                          24 h    2.4 × 10.sup.5                                                                3.9 × 10.sup.3                                                                7.5 × 10.sup.3                                                                2.1 × 10.sup.1                                                                9.3 × 10.sup.3                                                                1.5 × 10.sup.2                          __________________________________________________________________________      Data represent most probable number MPN/g beef.                          

                  TABLE 6                                                          ______________________________________                                         Sampling                                                                              H.sub.2 O @                                                                             10% TSP @   H.sub.2 O @                                                                           15% TSP @                                   Time   70° F.                                                                           70° F.                                                                              120° F.                                                                        120° F.                              ______________________________________                                         0          1.7 × 10.sup.5                                                                    7.8 × 10.sup.3                                                                     6.5 × 10.sup.4                                                                  4.3 × 10.sup.3                      15  sec    4.6 × 10.sup.4                                                                    1.1 × 10.sup.4                                                                     5.7 × 10.sup.4                                                                  3.7 × 10.sup.3                      5   min    1.2 × 10.sup.5                                                                    1.7 × 10.sup.3                                                                     1.1 × 10.sup.4                                                                  8.3 × 10.sup.3                      1   h      6.3 × 10.sup.4                                                                    9.4 × 10.sup.3                                                                     2.2 × 10.sup.4                                                                  8.4 × 10.sup.3                      6   h      1.3 × 10.sup.5                                                                    3.9 × 10.sup.4                                                                     4.8 × 10.sup.4                                                                  8.5 × 10.sup.2                      24  h      1.5 × 10.sup.5                                                                    8.0 × 10.sup.4                                                                     8.6 × 10.sup.4                                                                  1.4 × 10.sup.3                      ______________________________________                                    

The above examples demonstrate that trisodium phosphate either alone or in combination with other additives, with the proviso that the treatment solution of orthophosphate is free of alcohol, nitrite or nitrates, and ascorbic acid, has great potential for use in eliminating salmonella and other organisms red meat carcasses. 

What is claimed is:
 1. A process for treating red meat comprising treating the surface or internal organs of eviscerated red meat, with a treatment solution comprising trialkali metal orthophosphate at a pH exceeding 11.5 and at a temperature of up to about 60° C. in an amount and for a period of time effective to retard, reduce or remove bacterial contamination and/or growth without substantial color change caused by the treatment solution pH and with the proviso that the solution does not contain alcohol, nitrate or nitrite, or ascorbic acid.
 2. The process as recited in claim 1 wherein said orthophosphate is trisodium orthophosphate and the amount of orthophosphate is about 4% to saturation.
 3. The process as recited in claim 2 wherein the treatment solution is applied prerigor and the time of treatment is up to 30 minutes.
 4. The process as recited in claim 3 wherein the treatment solution is sprayed on the red meat for 2 seconds to 15 minutes.
 5. The process according to claim 2 wherein the amount of trisodium orthophosphate ranges from about 4% to about 20%.
 6. The process according to claim 5 wherein said process is useful in reducing or retarding E. coli 0157:H7.
 7. The process as recited in claim 1 in which the red meat is selected from the group consisting of pork, beef, veal, mutton, lamb and goat.
 8. The process according to claim 7 wherein said process is useful in treating internal organs.
 9. The process as recited in claim 1 in which the treatment solution pH ranges from 11.6 to about 13.5 and the solution is applied prerigor.
 10. The process as recited in claim 1 in which the temperature of the solution is equal to or less than 40° C.
 11. The process as recited in claim 1 in which the treatment solution further includes other ingredients for preservation, waterholding, cleaning, flavoring, coloring, and the like.
 12. The process as recited in claim 1 wherein treatment is conducted below 10° C. and is followed by conventional process of the red meat.
 13. The process of claim 1 in which salmonella, campylobacter, E. coli, and spoilage bacteria are retarded, reduced or removed by treatment with 4% to saturation of trisodium phosphate solution.
 14. A process for reducing or retarding E. coli 0157:H7 on red meat comprising treating the surface or internal organs of eviscerated red meat with a treatment solution comprising trialkali metal orthophosphate at a pH exceeding 11.5 without substantial color change caused by the treatment solution pH with the proviso that the solution does not contain alcohol, nitrate or nitrite, or ascorbic acid.
 15. The process according to claim 14 wherein said treatment solution comprises trisodium orthophosphate present in an amount of about 4% to saturation.
 16. The process according to claim 15 wherein the amount of trisodium orthophosphate ranges from about 6% to about 15%.
 17. The process according to claim 16 wherein the temperature of the treatment solution is below about 60° C. 